Oxidation of butane to maleic anhydride using butane-rich feed

ABSTRACT

In the oxidation of n-butane to maleic anhydride using a variety of catalysts, a substantial improvement in the selectivity for maleic anhydride is obtained when the mole ratio of butane to oxygen is greater than 1:4.

Unlted States Patent 1 1 [111 3,899,516

Dickason Aug. 12, 1975 [54] OXIDATION OF BUTANE TO MALEIC 2,691,660 10/1954 Hartig 260/3468 ANHYDRIDE USING BUTANE RICH FEED 3,478,063 11/1969 Fredrichsen et al. 260/3468 3,832,359 8/1974 Freenk et a] 260/3468 [75] Inventor: Alan F. Dickason, Chester, Pa. [73] Assignee: Sun Ventures, Inc., St. Davids, Pa. FOREIGN, PATENTS OR APPLICATIONS 2,072,336 9/1971 France 260/346.8 [22] Filed; Oct. 17, 1973 [21] Appl. No.: 407,347 Primary Examiner-Harry I. Moatz Attorney, Agent, or Firm-George L. Church; Donald 52 US. (:1 260/346.8 A; 252/435; 252/467; Stanford Back 252/468; 252/470 [51] Int. Cl. C07D 307/60 [57 T T [58] Field of Search 260/3468, 435, 467, 468,

260/470 469 In the OXIdaUOIl of n-butane to maleic anhydrrde uslng a variety of catalysts, a substantial improvement in the [56] References Cited selectivity for maleic anhydride is obtained when the mole ratio of butane to oxygen is greater than 1:4.

12 Claims, N0 Drawings OXIDATION OF BUTANE TO MALEIC ANHYDRIDE USING BUTANE-RlCI-I FEED CROSS-REFERENCE TO RELATED APPLICATIONS The subject matter of the present case is closely re lated to that of the following copending applications:

SERIAL NI'MBI'IR 111111 the increased activity permits, if desired, operation at lower temperatures instead to obtain the same yields as compared with operating in the conventional hydrocarbon-lean mode.

lNVI-INl'ORls) Oxidation of Butane to \lzilcic Alll'| \'tll'l(lC Oxidation of Butane lu Malt-iv; Anltulride ()\itlatinn of Butane to Maleic Anlndritlc S.N.( Docket $72 12 S..'\'.( Docket S-7I-2ll1l SN. Docket S ll-2101.1

Dickason et a1 Dickason et :11

BACKGROUND OF THE INVENTION This invention relates to an improved process for the production of maleic anhydride. More particularly, this invention relates to a process for the vapor phase catalytic oxidation of n-butane to maleic anhydride using high ratios of butane to oxygen in order to improve the selectivities for said maleic anhydride.

In the three copending applications listed in the above paragraph, there is described a general method for the vapor phase oxidation of n-butane to maleic anhydride wherein, in each instance, a novel catalyst system is employed. Also disclosed therein are other like catalytic oxidations known in the prior art. In each case, however, the general mode of operation taught is to run the vapor phase reactor with a hydrocarbon-lean gas mixture relative to the amount of oxygen employed, i.e., less than about 2% butane. This is customarily done for safety purposes, so that mole ratios of about 1:4 or lower, and preferably ratios of 1:10 down to about 1:20 of butane to oxygen are the general rule. Under these conditions, it has been found that the selectivity for maleic anhydride is generally between 25 and'50 percent.

Other relevant prior art generally pertaining to the subject matter of this invention is represented by Belgian Pat. No. 791,294, and German Patent publication No. 2,256,909.

SUMMARY OF THE INVENTION It has now been found that, contrary to general prac- 'tice and expectations, when the oxygen is employed as pure oxygen rather than diluted with inert gases, e.g., with nitrogen as in air, and the concentration of butane relative to the oxygen is increased to ratios of greater than l:4, preferably greater than 1:1, in order to operate outside the explosive limits, the selectivity for maleic anhydride is increased about percent over what is obtained with a hydrocarbonlean feed but without any dangerous side effects. Thus, it has been found that ratios of greater than 1 :4 may be employed, and preferably ratios in the range of about 1:1 to 20:1 of butane to oxygen. Furthermore, a significant increase in spacetime-yield is obtained when the C, n O ratio is changed and substantially pure oxygen is employed in place of air. By substantially pure oxygen is meant oxygen which may contain up to about 5 percent of inert gaseous impurities.

This feature is of great economic significance when designing a commercial plant. There is an obvious ad- DESCRIPTION OF THE INVENTION The vapor phase oxidation of butane to maleic anhydride, in accordance with the process of this invention, may conveniently be carried out by passing the butane, together with oxygen over a bed of suitable catalyst at temperatures of from about 350 to 650C, and preferably about 400 to 500C, at contact times of from about 0.001 sec. to 10 sec., and preferably about 0.1 to 2 sec., and at pressures ranging from atmospheric pressure to about 100 lbs/in. where the catalyst bed may be either a fixed bed, a fluidized bed, or a moving bed. The concentration of oxygen, relative to the amount of butane should, of course, be in accordance with the aforedescribed ratios.

The catalysts which may be used include any catalyst known to oxidize butane to maleic anhydride, and is not intended to be limited to the examples shown or otherwise referred to. Thus, included amongst the catalysts which are suitable for purposes of this invention are such prior art metals, metal oxide and/or metal salt combination as Co/Mo (US. Pat. Nos. 2,625,519 and 2,691,660); V/Mo/alkali metal chloride (US. Pat. No. 3,074,969); V/P (US. Pat. No. 3,293,268); V/Ti/Mo- /Al (US. Pat. No. 3,055,842); as well as the four component vanadium catalysts as Fe/V/Sb/MoO, plus one other metal (German Pat. No. 2,138,692).

Also included amongst the catalysts which may be used in this process are those taught in the three crossreferenced cases of Dickason, and Dickason et a1. listed above, which three cases are hereby expressly incorporated herein by reference. In the first of these cases, Ser. No. 407,340, filed Oct. 17, 1973, there is disclosed a butane to maleic anhydride oxidation catalyst comprising Sb/Mo and a third metal selected from the group consisting of Ni, Co, Cu and Zn, wherein said catalyst contains at least about 40 atomic percent antimony, less than about 20 percent molybdenum, and less than about 40 percent of said third metal.

In the second case, Ser. No. 407,342, filed Oct. 17, 1973, there is disclosed a catalyst comprising a V/ P catalyst containing a third metal selected from the group consisting of Fe, Co, and Ni, alternatively with tungsten as a fourth component. This catalyst is preferably supported on TiO as an inert carrier. The composition of this catalyst is desirably at least about 5 mole percent vanadium, less than about mole percent phosphorus, and less than about 50 mole percent of the iron, cobalt or nickel.

Still another catalyst which may be used in the process of this invention is disclosed in Ser. No. 407,346, filed Oct. 17, 1973, in which the composition is the same as that of Ser No. 407,342, filed Oct. 17, 1973 except that Ca, Ba, or Mg is substituted for the Fe. Co. or Ni.

The invention will now be illustrated by the following examples.

ring with a plastic spatula until the powder is all wetted. Phosphoric acid (85% H PO 29.0 gm) is then added and stirred until thoroughly mixed.

The mixture is then evaporated to a thick paste on a steam bath, and dried at 1 lO120C for 16 hours. The EXAMPLE I dried cake is broken to pass a 4-mesh screen, calcined Preparation of a antimony-nickel-molybdenum catalyst f 50 45()C over 4 hour and then held at 450C Antimony pentachloride (SbCl 149.5 g.) was added for 4 hoursslowly to a stirred solution of nickel chloride hexahy- EXAMPLE 4 drate (NiC1 6H O, 118.9 g.) in 500 milliliters of distilled water. (The temperature increased from 28C to A gaseous mlxtllre of butane (62 mole and 42C). The pH of the mixture was adjusted to 6.5 with gen 9' Passed Over gms) i a concentrated aqueous ammonia using an ice bath to Vanad'umi Phosphorus catalyst SuPPOrted T' keep the temperature below 60C. The mixture was P l- Example 3) contamffd "l X 6 Inch then stirred for 45 minutes filtered, the filter Cake stainless steel reactor. The contact (line-1S 0.21 sec. at washed three times by resuspension in 500 milliliter 478 The selectwlty t male1c anhydnde l 65 mole portions of distilled water and filtered again. The moist at Percent Converslons filter cake was then mixed with ammonium molybdate EXAMPLE 5 [(NH Mo O 4H O, 1.1 g.] in 100 milliliters of dlstilled water evaporated to a thick paste on a steam Preparatlon ofa vanadulm'calclurfl'phorphorus bath, and dried at 110-120C for 16 hours. The dried catalyst Supported on 02 cake was broken to pass a 4'mesh screen and calcined A warm Solution f vanady] oxalate 9 75 in 700C over 8 hours then held at formamide (16.25 gm) and distilled water 12.5 gm) is C l hoursadded to a mixture of ferric phosphate (Ca P0 x EXAMPLE 2 H O, 23 75 gm) and titanium dioxide (Tio l 1.25 gm), stirring with a plastic spatula untilthe powder is A gaseous mlxmre of butane mole n Y- all wetted. Phosphoric acid (85% n ro 290 gm) is mole was passed 9 the antimony then added and stirred until thoroughly mixed. I mckel'molybdenum catalyst m Inch X 2 /2 f 30 The mixture is then evaporated to a thick paste on a stainless steel reactor. The condltlons and results ob- Steam bath and dried at 1 e e for 16 hours The tained are summarized in the following table. For comdried cakeis broken to pass a 4 mesh screen, calcined parison a second run employing the butane: oxygen rafrom 6 0 over 4 hours and then held at 450C. tios of the prior art are also set forth. for 4 hours I TABLE I r Space 'l'imc Temp. )2 'limc ('illillyst C (Sec) (C) Com. Scl. Yield Sh/Ni/Mu l.(l:l 0.20 42s 2.4 5l m3 1:21) 0.9x 400 (is 25 30 From the foregoing comparison it will be seen that a EXAMPLE 6 significant increase in space-time-yield is obtained A gaseous mixture of butane (65 mole and wherein said yield increased from 30 to 103 when the gen (35 mole'%) is passed over 2.0 mls. (13 gms) of butane 2 Oxygen ratlo was changed m 1:20 to a vanadium, calcium, phosphorus catalyst supported on and P fY exployefl m Place of In terms of TiO (as prepared in Example 5) contained in a A X 6 economlc slgmflcance thls means that a reactor Slze inch stainless steel reactor. The contact time is 0.19 could be reduced by a of sec. at 500C. The selectivity to maleic anhydride is 56 EXAMPLE 3 mole at 0.51 conversion.

Preparation of an iron-vanadium-phosphorus catalyst EXAMPLE 7 Supported on Tloz In accordance with the procedures of Example 2, a A warm solution of vanadyl oxalate (9.75gm) in series of runs were carried out under various condiformamide (16.25 gm) and distilled water 12.5 gm) is tions, using different catalysts and butane oxygen raadded to a mixture of ferric phosphate (F P X 2 tios (including some of the prior art for comparative 23-75 9") a titanium diOXide zr l g Stir purposes). The results are shown in the following table.

7 TABLE ll RLIN ('A'IALYST 1o list-u.) 'l'lnNlll'C) (oily slili x'l. I s'l'v l (u/Mu 1.30 .111 47s 55 31 34 3 l .(u l .2: Mix 1.4 4-1 46 .1 1.20 .m 55m 36 4: 20

4 3:1 .:l 475 L14 (is do 5 l-c/P/"l'i 1:21! .33 551! 45 20 (i \"lu. 1""l'i iii-l I" 11* 1 us (.1. llw

The invention claimed is:

1. In a process for the catalytic vapor phase oxidation of butane to form maleic anhydride, the improvement wherein the oxidant is substantially pure oxygen, the ratio of butane to oxygen is greater than about 1:4, and the catalyst is a vanadium-phosphorus catalyst containing a third metal component selected from the group consisting of calcium, barium, and magnesium.

2. The process of claim 1 wherein the catalyst is supported on TiO 3. The process of claim 1 wherein the mole ratio of butane to oxygen is from about lzl to 20:1.

4. In a process for the catalytic vapor phase oxidation of butane to maleic anhydride, the improvement wherein the oxidant is substantially pure oxygen, the ratio of butane to oxygen is greater than about 1:4, and the catalyst is an antimony-molybdenum catalyst containing a third metal component selected from the group consisting of nickel, cobalt, copper, and zinc.

5. The process of claim 4 wherein the mole ratio of butane to oxygen is from about 1:1 to 20:1.

6. ln the process for the catalytic vapor phase oxida tion of butane to maleic anhydride, the improvement wherein the oxidant is substantially pure oxygen, the ratio of butane to oxygen is greater than about 1:4, and the catalyst is a vanadium-phosphorus catalyst containing a third metal component selected from the group consisting of iron, cobalt, and nickel.

7. The process of claim 6 wherein the catalyst contains a fourth metal component comprising tungsten.

8. The process of claim 6 wherein the catalyst is supported on TiO-;.

9. The process of claim 7 wherein the catalyst is supported on TiO 10. The process of claim 6 wherein the mole ratio of butane to oxygen is from about 1:1 to 20:1.

1 1. In the process for the catalytic vapor phase oxidation of butane to maleic anhydride, the improvement wherein the oxidant is substantially pure oxygen, the ratio of butane to oxygen is greater than about 1:4, and the catalyst is a cobalt-molybdenum catalyst.

12. The process of claim 9 wherein the mole ratio of butane to oxygen is from about 1:1 to 20:1.

=l =l =l 

1. IN A PROCESS FOR THE CATALYTIC VAPOR PHASE OXIDATION OF BUTANE TO FORM MALEIC ANHYDRIDE, THE IMPROVEMENT WHEREIN THE OXIDANT IS SUBSTANTIALLY PURE OXYGEN, THE RATIO OF BUTANE TO OXYGEN IS GREATER THAN ABOUT 1:4, AND THE CATALYST IS A VANADIUM-PHOSPHORUS CATALYST CONTAINING A THIRD METAL COMPONENT SELECTED FROM THE GROUP CONSISTING OF CALCIUM, BARIUM, AND MAGNESIUM.
 2. The process of claim 1 wherein the catalyst is supported on TiO2.
 3. The process of claim 1 wherein the mole ratio of butane to oxygen is from about 1:1 to 20:1.
 4. In a process for the catalytic vapor phase oxidation of butane to maleic anhydride, the improvement wherein the oxidant is substantially pure oxygen, the ratio of butane to oxygen is greater than about 1:4, and the catalyst is an antimony-molybdenum catalyst containing a third metal component selected from the group consisting of nickel, cobalt, copper, and zinc.
 5. The process of claim 4 wherein the mole ratio of butane to oxygen is from about 1:1 to 20:1.
 6. In the process for the catalytic vapor phase oxidation of butane to maleic anhydride, the improvement wherein the oxidant is substantially pure oxygen, the ratio of butane to oxygen is greater than about 1:4, and the catalyst is a vanadium-phosphorus catalyst containing a third metal component selected from the group consisting of iron, cobalt, and nickel.
 7. The process of claim 6 wherein the catalyst contains a fourth metal component comprising tungsten.
 8. The process of claim 6 wherein the catalyst is supported on TiO2.
 9. The process of claim 7 wherein the catalyst is supported on TiO2.
 10. The process of claim 6 wherein the mole ratio of butane to oxygen is from about 1:1 to 20:1.
 11. In the process for the catalytic vapor phase oxidation of butane to maleic anhydride, the improvement wherein the oxidant is substantially pure oxygen, the ratio of butane to oxygen is greater than about 1:4, and the catalyst is a cobalt-molybdenum catalyst.
 12. The process of claim 9 wherein the mole ratio of butane to oxygen is from about 1:1 to 20:1. 